This invention relates to foamed metals and to a method for making foamed metals and metal alloys. More specifically, this invention relates to foamed metals and metal alloys and to a method for making foamed metals and metal alloys which have a closed cellular structure.
Foamed metals and metal alloys, that is, metals and alloys which have a density less than that of the solid material, have a number of unique and desirable characteristics such as a high stiffness-to-density ratio, high damping characteristics, high impact resistance, and low thermal conductivity. Such materials are electrically conducting and can be fabricated by conventional metalforming techniques such as welding, brazing, etc.
Materials having these characteristics are useful in a number of applications: for example, materials having a high stiffness-to-density ratio, high damping coefficients and high impact resistance are desirable in aircraft components such as helicopter blades. High damping coefficients and high impact resistance will be useful in preparing a lightweight armor, while material having high resistance to external pressure would be excellent for preparing structural components for deep-sea equipment. A hydrogen storage cell of foamed titanium would permit the storage of a large quantity of hydrogen as titanium hydride, and a nuclear reactor fuel such as a foamed plutonium alloy would permit a compact reactor power source by allowing room within the fuel element for swelling and gas formation.